This invention relates to catalytic hydroformylation processes for converting olefins to aldehydes.
In the hydroformylation of olefins, carbon monoxide and hydrogen add to the olefin under conditions of elevated temperature and pressure to produce mixtures of linear and branched aldehydes. Catalytic hydroformylation of olefins is known as the "oxo" process. Depending on the olefin type, the catalyst, the solvent and reaction conditions, it is known that selectivity to linear or branched aldehydes, reaction rate and yields can be influenced. For example, cobalt corbonyls and rhodium complexes containing tertiary phosphine or phosphite ligands are known hydroformylation catalysts. See "Oxo Process," Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition (1981), 16, 637-653; Evans, et al., J. Chem. Soc., A, 3133 (1968); and Pruett and Smith, J. Org. Chem. 34, 327 (1969). Platinum (II) complexes containing tertiary phosphine are used to obtain higher ratios of straight chain to branched chain aldehydes. See Hsu and Orchin, J. Amer. Chem. Soc., 97, 3553 (1975); Schwager and Knifton, J. Cat., 45, 256 (1976); U.S. Pat. No. 3,981,925 and 3,996,293. Ionic forms of platinum (II) catalysts for hydroformylation of olefins are disclosed in U.S. Pat. Nos. 3,876,672, 4,101,564 and 4,155,939.
However, the platinum (II) catalysts, although somewhat effective in favoring selective formation and high yields of the more desirable straight chain aldehydes, and sometimes at relatively mild conditions of temperature and pressure, nevertheless tend to reduce the reaction rate and therefore diminish the economic importance of the process. Moreover, the large proportion of halides in such catalysts introduces a considerable potential for corrosion of manufacturing equipment, thereby requiring large capital outlays for corrosion resistant equipment and lines, and thus reducing economic value of the catalysts.